Rockwell Automation 1785-Lxxx Enhanced and Ethernet PLC-5 Programmable Controllers - Manual (Page 55)

Publication 1785-UM012D-EN-P - July 2005
Addressing I/O and Controller Memory 4-11
Understanding Data Storage (Data-Table Files)
The controller divides data storage into:
• Types that let you specify different formats and ranges to accommodate
different types of data. For more information on the different types of
data files, see on page 13.
• You can create multiple files of a given type. Files let you group and
organize logically related data. When you need to access data, you
specify the file in which the data is stored.
• Some types of files are made up of 16-bit words. Floating-point words
are 32 bits. When you need to access this data, you specify it with a
formatted address.
• Each word contains multiple bits. This is the smallest division of data.
A bit contains a value of zero or one. When you need to access this
data, you specify it with a formatted address.
• Some types of files are divided into structures used to control
instruction elements. These structures are subdivided into members at
the bit or word level. When you need to access this data, you specify it
with a formatted address.
You can also organize data within files into data blocks to group and organize
logically related data. When you need to access this data, you specify only the
starting address within the file (and length) instead of each individual address.
When you organize data, group data by similar kind, such as:
• results of calculations
• batch recipes
Because of the structure of block-transfer instructions, you must group data
such as:
• inputs from analog modules
• outputs to analog modules
File #
Integer
File 999
Integer Data
Table Files
File 7
2
1020
64
7779
File 7
Integer
Files
(Sample Data)
Words
0 276 0 0 0 0 0 0 1 0 0 0 1 0 1 0 0
Integer
Natural binary bit pattern for 276
(decimal format)
File
2760
432
Timer File #
Timer #
preset .PRE
accumulated .ACC
structure members
.EN .TT .DN
File #
Starting addr
up to 1000
recipe "A" data
recipe "B" data
production counts
words
(Length)
Starting addr
(Length)
Starting addr
(Length)